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The connecting rod is one of the five big engine, engine is important safety pieces. The quality of the connecting rod directly influence engine performance and security. The connecting rod from the structure is not complex, but the connecting rod belongs to the typical irregular parts and high accuracy, connecting rod processing technology is more complex. This article through to the connecting rod processing technology introduction, and targeted support for connecting rod broken of new technology and new materials for specific process analysis, to realize the development of the advanced nature of the connecting rod processing.42553
The connecting rod is to transfer the power of the important moving parts, it small head with the pistons for reciprocating motion, the major part of the crankshaft rotary motion, as with the rod body in size head movement under the synthesis of swing. In addition to withstand cyclical change, as well as gas impact bear the larger the inertial force. This requires connecting rod fatigue resistance, impact resistance, and have the enough strength, stiffness and good toughness.
Because the structure of the engine is different, connecting rod structure vary slightly. But its basically piston sales by KongDuan (small head end), crankshaft pin KongDuan (big head end) and rod body of three parts. The crankshaft pin KongDuan for separate structure, body and cover bolted connection. The size of the connecting rod head height of the different structure, according to a contour and high two kinds, ranging in V type engine, in order to enable the compact structure, the connecting rod often use the structure of high range.
The modern high-performance engines to the requirements of the connecting rod is light weight, high strength, good stiffness, the inertial force is small, as far as possible the reinforced technology and so on. Development trend is short connecting rod structure. Engine moving parts of the weight loss, and help to reduce the energy consumption and noise; Can improve engine emissions. On short of connecting rod demand because the engine is headed in small size and large power the direction of development.
The connecting rod mechanical processing of the main technical requirements herein, small head connecting rod IT7 cylindricity 0.01 mm, surface roughness Ra1.6 um
The big end hole IT5 ~ IT6, surface roughness Ra0.8 um
The connecting rod size head hole center distance + 0.03 ~ 0.05 mm
The connecting rod size head hole parallel degree 0.02 ~ 0.06/100 mm
The big end at both ends of the big hole facing verticality 0.06 ~ 0.1/100 mm, thickness tolerance (0.05 ~ 0.08 mm), and the surface roughness Ra0.8 um.
The connecting rod weight tolerance + 3 ~ + 8 g
The connecting rod in the work under the multiplex alternating load, require a high intensity, the blank of the high strength carbon steel and mostly in carbon steel alloy die forging and into. In recent years, because of the connecting rod processing using support of new technology and broken powder metallurgical technology, the development of high carbon steel, malleable iron and powder metallurgy material also is widely used. In addition, some with new form and microstructure of materials, such as composite materials, aluminum alloy material fiber reinforcement can be used.
Try to reduce blank surplus, improve the precision and reduce blank cutting force and the improvement of the machining efficiency.
Every car number, production requirements of the machine tool, beat short machining efficiency and high precision.
Due to poor, connecting rod itself rigid in positioning and clamping point when the choice, avoid need special attention in locating produce larger error and not stable in clamping deformation and the influence of the machining accuracy.
Should follow the principle of unified standards, trying to avoid the benchmark replacement, to reduce the positioning error.
Because of the connecting rod weight in a special requirements, so assembly shall be properly arrange weighing, to weight, weight working group.